Why most butterfly caterpillars rely on single or very few type of host plants for food?
Like some other insects, butterfly caterpillars eat only very few type of host plants. The Wanderer caterpillars only feeds on the milkweed plants and the Birdwing caterpillars only feeds on the Birdwing Vine. This single host plant phenomenon is very common in butterflies and it is not an advantage to the butterflies. We observed the following situations that contributed to this phenomenon. The following discussions can also explain why parasites are usually specialize on a single host type.
